Question 1
To find the unit rate, you need to set the buses value to 1 by dividing b 20. Since you divided the buses by 20, you need to divide the people by 20. When you do so, you will see that the unit rate is 15 1/5 or 15.2 per bus.
Question 2
The proportion is false because for it to be proportional, the second fraction would need to be 6/4/12.